1/8 Porsche 935/78 'Moby Dick'

[ScratchBuilt]

Hello again,

Last week was all about laying-up fibreglass. There are still more parts to be made - rear wing mainplane and endplates, etc - but I had enough moulds ready to start a new batch.

So, here's the basic toolkit:



Aeropoxy resin and hardener from Deluxe Materials, petroleum jelly as a release agent, mixing pot, and small brush. The Aeropoxy is poured in the ratio of 3 parts resin to 2 parts hardener, or 7.5ml to 5ml; a quick stir to mix it all together and it's ready to go. Given that it's been quite warm recently, each mix would give me about 30 minutes to work with before starting to go off. Normally this is enough time, but not always...

Next up, the fibreglass cloth:



From left to right, 0.6oz, 1.5oz, and 2.3oz; I've also got some 1oz and 2oz available, but these were not used for laying-up these parts. As you can see, the lightest 0.6oz cloth is rather fine - it frays very easily, but is the easiest to work over the curves and changes of direction. The heavier cloths are better suited to panels with less detail, but it's easy enough to mix-and-match and add odd bits of heavier cloth in strategic positions.

When first mixed, the resin is quite fluid and brushes onto the mould easily. The first layer of cloth is always the messiest, as you're brushing the resin onto the petroleum jelly - the coverage can sometimes be hit-and-miss.





The benefit of the 0.6oz cloth is that it can be worked into the corners, as shown above on the front bulkhead mould. I try to keep each layer of cloth as a single intact piece, but on more complicated moulds it is often necessary to make small cuts to allow it to take the correct shape. Rotating the direction of the weave between layers is also a good idea, as it improves the strength and stiffness of the finished part.

Whenever I'm laying up, I always work on the more complicated moulds first while the resin is at it's most fluid. You know when it's beginning to go off when the cloth starts sticking to the brush as you're trying to brush it down! At this point there's no chance of continuing - mix up a new batch of resin in a fresh pot, and use a fresh brush. Using the old pot or brush will only kick-start the reaction in the new mix, giving you even less time...

So, I put four layers of cloth onto each mould. A couple of layers of 0.6oz to start with, then 1.5oz. The front bulkhead lower section received a layer of 2.3oz, rather than the second layer of 0.6oz. For the final layers on the more complicated moulds I did some trimming and cutting to vary the lay-up. For example, on the rear bumper section:



A smaller piece was then added over the middle to complete the layer.

The final layer of cloth was added mid-morning Saturday, then left to harden. Last night I removed the panels from the moulds - in most cases you can get a length of thin cardboard inbetween and work the fibreglass loose. This becomes tricky when you have more complicated shapes, and the cardboard won't necessarily go where you want it to! The petroleum jelly does a good job, but it makes it a messy process.



Once off the moulds I gave everything a quick trim around the edges, then a scrub in warm soapy water. Now it's all about getting everything trimmed to shape properly, and smoothed-off: despite my efforts to remove the worst of the lumps and bumps between layers, the outer surfaces are in need of further attention.

Of course, new panels have to be offered up to the car as soon as possible - it's the rule!



I measured the thickness of the new panels - each one is typically around 0.6 to 0.65mm, which is okay. If they were intended to be more 'structural' I would possibly have added a fifth or even sixth layer of 1.5oz cloth, but for these parts it was unnecessary.

Finally for tonight, I've also been working on the right-hand rear bodywork support frame, and making a start on the extension for the tail support:



The tail support is all 1/8" ali tubing, and each side will be pinned into the back of the engine bay. Styrene tube would be easier to work with, of course, but there's going to be some load on here once the bodywork is fitted so ali was the better choice. I'll continue with this during the week, and make a start on trimming some of the new panels.

That's it for tonight!

SB

[nugundam93]

after all these updates, your lego jig system is still awesome appreciate you taking pics of the layup process!

[ianc911]

Great pics of the layup; was getting curious about that!

ianc

[ScratchBuilt]

Hmm...where have the last few weeks gone?

I've been saving all sorts of things for this update - it's not a case of lack of progress, it's more that I've been making progress in several directions at once! First up, continuing with the rear bodywork support frames:



The small diagonal tubes were particularly awkward - it didn't help that I wanted to pin both ends. As usual, the Lego helped to keep things in line.

Next, there are two small 'ears' which support the back end of the two outer wing panels. These were cut from solid styrene, with two drillings to pin them into the main ali tubes, and a third L-shaped pin to help anchor them in place:



The tricky part with these frames was how to secure them to the back of the chassis, to cope with the weight of the bodywork. Although I had added ali (or was it brass?) tubing inside the main styrene chassis tubes for strength a long time ago, this tube was pierced in several places where I'd pinned other tubes and brackets in place - so I couldn't sleeve the bodywork frame too far inside. To improve the situation, I filed the ends:



Here's the frames in place:



I've greenstuffed some of the joints already, including the two styrene 'ears' - the small L-shaped pin is buried inside. There's a couple of extra small details still to come, but these frames are now a permanent fixture. With the other small ali outrigger frames added too, there's suddenly a lot going on back there.

Moving on, here's the interior cover panel for the gearbox after an initial trimming and fitting session:



The fun part will be getting it to fit around the tubes of the main roof structure - more on this next time.

With the tail support frames fixed I could start trimming the main bumper section:



I wanted to keep the bumper in one piece for as long as possible, although in time it will be cut into three. It soon became clear that a mk2 version would be required - I needed a little extra material on the top and bottom edges to get a better fit with the outer wing panels, the centre section needed 'adjusting' to give me clearance for the turbo units, and the exhaust would need altering to get the hole in the right place! Other than that, it was fine...



You can see above where I've had to pull the bumper away from the main chassis frame - I've got to get the turbo assembly tucked away under there eventually. You also get an idea of how the outer section of the bumper will be added to the wing panel / fender.

So, last week was another fibreglassing session, starting with the mk2 bumper (with angled centre section):



...rear wing mainplane:



...and a folded panel for the endplates:



The foam core was wrapped in fibreglass cloth with no release agent - it wasn't coming out. Three layers of cloth, and that was that - a light, stiff wing plane. Keeping the foam core in place would present one obvious problem - how to glue the end plates? My solution was to drill two 1/8" holes into the end, then add a styrene 'plug' to which the end plate can be glued:



Finally, in amongst all this I've been fitting the mk3 front bulkhead. I used the mk2 version as a reference and fiddled with cardboard templates to improve the fit with the outer wing panels:



By the time of this final photo I'd added the channel for the steering column, some styrene detailing on the lower vertical section of the panel, and you can just see two small brackets down the bottom which are for 'bolting' the tube frame chassis to what's left of the 911 bodyshell:



So, plenty of progress and more to come. I hope to get more done with the rear wing this week, and will continue detailing the front bulkhead. A return to the cockpit and dashboard is looming, but I suspect that will be a job for my holiday later this month.

Have a good week,

SB

[nugundam93]

another awesome update!

[lasagna99]

I know i say nothing new,but your work is incredible...really...

[ScratchBuilt]

Hello everyone,

Odd time for an update (from me, anyway) but I've reached a good point in the build and wanted to show what I've been doing before getting on with the next job. I've certainly had a productive week, but I'll start with the mk2 bumper panel which made a brief appearance during the last update.

The extra height I added to the mould has allowed me to get a better fit where the outer ends of the bumper panel are wedged into the rear wings / fenders:





Getting this to work properly has been frustrating at times, and still needs more effort before I'm ready to start gluing parts together. I'm still reluctant to cut the bumper panel into the three sections just yet, as it's too useful to have it in a single piece. The angled panel over the top of the turbo units appears to work well - it should provide enough room for everything to fit. I'll return to these parts in a while.

Next, a piece of destruction rather than construction. When I had the mk1 version of the bumper panel I realised that the turbo exhaust pipes were not going to be in the correct position. I'd modelled them as being horizontal, but the engine actually sits in the car at nose-down angle - so the tailpipes were now pointing upwards. Now, I'm not claiming total accuracy for my bumper panel measurements, but I knew that I couldn't make it all work as it was - the best solution was to adjust the angle of the tailpipes. Rather than completely re-make these parts, I made a pair of new flanges from styrene tube and half-round section, then separated the old flanges from the tailpipes:



Moving on to this week, I decided to spend time on the rear wing - the mainplane was easy enough to trim to length, but that still left the main supports to work out. Once I'd settled on a shape for a template, I cut five panels for each support from a mix of 0.75mm and 0.4mm styrene, giving a total thickness of just over 3mm. I then added a length of 1/8" ali tube to create the leading edge, and to provide some strength and (hopefully) structure:



As I glued the styrene panels together I created a channel in the front edge, into which I could pin and glue the ali tubes:



From here it was a question of shaping and filling the trailing edge to create more of a teardrop profile, then adding brackets to attach the mainplane. The stay is small-diameter ali tube with a length of wire inside, with 3mm styrene rod and hex used to create the rod-end joint detailing. I kept a small piece of the left-over mainplane to use as a place-holder, rather than risk screwing up the actual part:



More of this later! Working on the wing and the engine cover extension panel gave me the impetus to tackle the rear grille. I worked out the basic measurements, and used one of my photos of the Silverstone Kremer 935 to get measurements for the spacing and the thickness of the grille slats. Thin styrene would have been ideal, but I was concerned about it distorting over time when glued together, so decided to use some of my flat-sheet fibreglass instead:



I cut the slats approx. 2.5mm wide by about 100mm long, then made the three supports from 2mm wide styrene. The fiddly part was adding the extra lengths of styrene across each support to create the correct spacing, but they were easy enough to trim to length afterwards. I then taped the three supports in place on a piece of cardboard, and started CA'ing the slats into position:



The slats were then cut to length to match the shape of the hole I was busy cutting into the rear deck. The hole edges were built-up with layers of styrene sheet and lengths of strip, as I worked out how to create the rest of the grille. Mesh was added to the underside and CA'd in place, with 3mm strip added as extra support. Finally, another styrene plate was cut which would fit around the whole lot and hold the grille in position:





Eventually the grille section will be painted black and can be glued into the rear deck panel. I've shaped the outermost ends of the slats to follow the curve of the bodywork, too. So far, I'm very happy with the result - it's not a job I'd planned to do this week, but given the time it's taken I'm glad I did!

Here's a shot of the rear deck with both the wing and grille panel in place - I trimmed the wing end-plates to size and pinned them into the styrene inserts shown last time. I added two small lengths of 1/8" ali tube into the trailing edge of the mainplane to create sockets - I then glued small styrene pegs onto the inner face of the endplates so that they were held at the correct angle. In time the whole lot will be glued together properly, but for now it's staying loose:



...and here's the required shot of the full car, with nose and whale-tail in position!



I have to do this from time to time, as it reminds me of what I'm working towards - getting the wing and grille sorted are both sizeable jobs crossed off the 'to do' list.

So, it's definitely been a productive week - and it's still only Friday. The next job I'm planning to tackle is the floor: I want to get some strength into the chassis structure, as the front end is vulnerable until the main roll-cage is added. Styrene sheet is too flexible, fibreglass is better but not good enough...maybe if I had a sheet of carbon-fibre I could use? More on this next time...!

All the best,

SB

[JesusM]

Ufff I need to see when the painting phase will be in place! !

[lovegt40]

amazing job. thanks for sharing sb.

[puffyrs]

Looking great.

[da_ashman]

Great Progress!!!

[Scalemodelfanatic]

There simply no words anymore to describe this work of engeneering in miniature....ALL the words that can be said....have been said....and this is an ongoing project, now let us try to imagine all this in it finished glory....supreme and sublime, THANK YOU SB, this is trully an inspiring and amazing journey in the art of miniature automobile modeling.

[lasagna99]

Incredible work!!!

[Niro750]

that is astounding, absolutely amazing work so far!

[kalax]

wow, wow, wow!!!